The installation of electrical wiring and equipment may involve installing electromechanical relays in a building or other structure. Electromechanical relays are used to switch electrical circuits between different states. For example, an electromechanical relay may include a switch in an electrical circuit that is used to switch the electrical circuit between an “ON” state in which current flows through the electrical circuit and an “OFF” state in which no current flows through the electrical circuit.
A relay assembly can include a sealed housing in which a relay used to actuate an electrical device is disposed. In some cases, unwanted pressure may be generated in the sealed housing. Such pressure may be generated from arcing caused by electrical switching contacts of the relay being engaged and/or disengaged.
For example, in a normal switching operation of a relay, setting the relay to an open or closed position (e.g., moving an armature between contacts of the relay) can cause arcing (i.e., sparks formed by current-carrying contacts being separated). The arcing can generate heat inside a relay assembly. The heat can increase pressure inside the housing of the relay assembly. Short circuit conditions in an electrical circuit that includes a relay may result in excessive current flowing through the contacts of the relay. A short circuit condition may be caused by, for example, an incorrect connection in an electrical circuit and/or a short in a line of an electrical circuit including the relay. Excessive currents caused by a short circuit can generate more powerful arcing in response to switching of the relay. More powerful arcing can generate more heat and thereby create larger increases in pressure than may be caused by normal switching operations of the relay.
Excessive amounts of pressure inside the housing of the relay assembly may exceed the ability of the housing to contain the pressure. The pressure exceeding the containment ability of the housing can cause the housing to rupture. Rupturing the housing may allow the expulsion of plasma, molten material, and/or projectile pieces in an uncontrolled and unpredictable manner, which may result in hazardous conditions.
Designing a housing that can withstand the explosive pressures resulting from high-current short circuit conditions of a relay can involve using a higher strength design with an increased number of fasteners or fasteners of higher strength. Use of such a higher strength design with an increased number of fasteners or fasteners of higher strength may increase costs associated with manufacturing a relay assembly.
It is desirable to provide a simplified relay assembly that can maintain structural integrity in response to excessive pressure being generated within the relay assembly.